make NavigationGesture part of public content API and use it outside content

content/browser/frame_host/navigation_handle_impl.cc

Index: content/browser/frame_host/navigation_handle_impl.cc
diff --git a/content/browser/frame_host/navigation_handle_impl.cc b/content/browser/frame_host/navigation_handle_impl.cc
index cbb04ad9e2a06efec23c67ab9d97788f845619ef..d1ae1c9f5fb777613532b49b44e70216be09f10a 100644
--- a/content/browser/frame_host/navigation_handle_impl.cc
+++ b/content/browser/frame_host/navigation_handle_impl.cc
@@ -206,8 +206,8 @@ const Referrer& NavigationHandleImpl::GetReferrer() {
   return sanitized_referrer_;
 }
 
-bool NavigationHandleImpl::HasUserGesture() {
-  return gesture_ == NavigationGestureUser;
+NavigationGesture NavigationHandleImpl::GetNavigationGesture() {
+  return gesture_;
 }
 
 ui::PageTransition NavigationHandleImpl::GetPageTransition() {
@@ -540,8 +540,7 @@ void NavigationHandleImpl::DidCommitNavigation(
   DCHECK(!render_frame_host_ || render_frame_host_ == render_frame_host);
   DCHECK_EQ(frame_tree_node_, render_frame_host->frame_tree_node());
   CHECK_EQ(url_, params.url);
-  // TODO(clamy): DCHECK that params.gesture matches
-  // has_user_gesture_. See crbug.com/667572.
+  // TODO(clamy): DCHECK_EQ(gesture_, params.gesture). See crbug.com/667572.
 
   method_ = params.method;
   transition_ = params.transition;